Duplex Air Compressor? - ANSWER Consists of two air compressors and two electric motors on one common receiver.
Dynamic Compressor? - ANSWER Adds kinetic energy to accelerate air and convert the velocity energy to pressure energy with a diffuser.
Effectively the branch pressure range on most ...
501 Instrumentation & controls 2024
LATEST UPDATE CORRECT 100%
Duplex Air Compressor? - ANSWER Consists of two air compressors and two electric motors on one
common receiver.
Dynamic Compressor? - ANSWER Adds kinetic energy to accelerate air and convert the velocity energy to
pressure energy with a diffuser.
Effectively the branch pressure range on most pneumatic controllers is? - ANSWER 3 to 15 lbs.
Electric Control Systems? - ANSWER A control system in which the power supply is - Low voltage (24
volts). Line voltage (120 or 220 volts). Rarely used due to the higher voltage (safety risks).
Electric Control Systems advantages? - ANSWER Provide adequate temperature control. Relatively safe.
Inexpensive. Flexible. Easily installed and maintained. Provides ON/OFF control.
Electric Control Systems Disadvantages? - ANSWER Cannot use in explosive areas. Generally, not able to
perform complex control sequences in commercial spaces. Does not allow analog (proportional) control.
Not designed to allow central reporting of failures and alarms.
Electric Control Systems Use? - ANSWER a variety of mechanical devices to control the state of the
electrical circuit, such as Bimetallic element in a thermostat. Bending metal causes contacts to close or
open. Contacts make or break a circuit which energizes or de-energizes the heating equipment.
Enthalpy is? - ANSWER the total heat contained in a material. The sum of latent and sensible heat,
expressed in btu/lb. of moist air.
Equalizing Run Time does what? - ANSWER equalizing run time with the air compressor system extends
the operational life of the two mechanical systems. Use of lead/lag switch.
,Fahrenheit is - ANSWER fresh water at normal atmospheric pressure (14.7P.S.I.A) 32F. is freezing, 212F. is
boiling.
Feedback is? - ANSWER The measurement of the results of a controller action by a sensor or switch.
Backup Compressed Air? - ANSWER System should have a backup air supply. Keeps proper operation of
the controllers and comfort of the occupants.
Blank is the number of positions an actuator will assume when the control signal is slowly changed 0-
100%? - ANSWER resolution
A blank is a device used to measure relative humidity? . - ANSWER hygrometer
A blank is installed in a compressed air system to deliver constant and reduced pressure to components
in the system? - ANSWER pressure regulator.
A bi metallic sensing element operates on the principal that when the heat is applied different metals
expand at? - ANSWER different rates.
A common air pressure applied to the supply of a pneumatic controller is? - ANSWER 18 P.S.I.G.
A control system is comprised of a sensor, controller, and a controlled device to maintain - ANSWER a
specific controlled variable value in a building space, pipe, or duct.
A device used to determine the relative humidity is called a? - ANSWER psychrometer.
A diverting switch is used to? - ANSWER manually change air line connections.
A heating thermostat closes blank? - ANSWER on temperature drop.
, A minimum code requirement for compressed air receiver would be? - ANSWER All of the above, vessel
must have a pressure gauge, safety valve, and a bottom drain.
A normally closed pressure electric switch is made when? - ANSWER no air is applied to its bellows.
A three-way diverting valve? - ANSWER has two outlets and one common inlet.
A three-way mixing valve? - ANSWER has two inlets and one common outlet.
Actuators are? - ANSWER Device that accepts a signal from a controller and causes a proportional
mechanical motion to occur.
Actuators modulate from full open to fully closed position as changes occur at the controller is an
example of? - ANSWER proportional control.
Air Compressor Stations are? - ANSWER Devices used to achieve the proper air quality: Filters, Dryers,
Reducing valves.
Air Compressor Takes air from the atmosphere and compresses it to increase its pressure, Converts
mechanical into? - ANSWER potential energy.
Air handling units? - ANSWER A device that conditions and distributes air throughout a building
Air Line Filters? - ANSWER Device consists of a housing containing a centrifugal deflector plate and a
small filtration element.
Air-conditioning is the control of? - ANSWER temperature, humidity, purity, distribution of air.
All HVAC control systems operate using the same set of control principles Include - ANSWER Setpoint,
Control point, Offset, Feedback.
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